Only about a quarter of the at-risk population statewide has received the H1N1 vaccine, meaning it will be a while before the flu vaccine becomes available for everyone else.

"We're happy with the way distribution has gone," state Department of Health spokeswoman Holli Senior said yesterday. "We certainly understand there are frustrations, and at times we've been frustrated. But we continue to target the recommended priority groups, and we're continuing to push out vaccine to providers to reach those individuals."

Ms. Senior said that about half of the state's 12 million people fall into the high-risk groups for swine flu. To date, the state has received 1.7 million doses that have been distributed exclusively to children and young adults between 6 months and 24 years old; people who live with or care for children under 6 months old; pregnant women; health care and emergency medical services personnel; and people 25 to 64 with underlying medical conditions.

Before making it available to anyone who wants the vaccine, the state will fill all pre-orders from physicians, hospitals, schools and colleges and assure there are enough doses for the at-risk groups served at statewide clinics.

Also yesterday, the chief health officer at the U.S. Centers for Disease Control and Prevention apologized for the frustration people have felt due to limited supplies of H1N1 vaccine.

Dr. Anne Schuchat, director of the National Center for Immunization and Respiratory Diseases, said she expects vaccine distribution to proceed more smoothly in the future.

The CDC predicted months ago that vaccine distribution would be "messy," and that prediction has proven to be valid.

The Associated Press noted in a story this week that health officials have been terrible in predicting when and how much vaccine would be available. So far 54.1 million doses have been distributed nationwide, including 11 million in the past week. But officials had predicted that about three times that amount would be available by now.

Other complaints include vaccine shipments that have been inexplicably lopsided. For example, smaller counties in Illinois and California have received the same amount of vaccine as counties with seven times as many people.

Despite all that, the effort to develop and distribute a safe and effective vaccine against a potentially deadly virus has been herculean.

"You have a brand-new disease that gets identified in April. By October, you have a vaccine for it. By any standards, it's a miracle," said Dr. Diane Helentjaris, director of the Virginia Department of Health office handling the swine-flu response.

But complaints continue to mount, prompting lawmakers this past week to hold hearings in Washington, D.C., and elsewhere to press for explanations.

Arthur Caplan, director of the University of Pennsylvania's Center for Bioethics, told AP that health officials should have done more to make sure limited doses got to the people most at danger. And he said they should have been tougher on nurses and other health-care workers who are putting patients at risk because the workers declined to get shots.

But the CDC said the main issue is insufficient vaccine from manufacturers, something the government can't control.

Today at four clinics, the Allegheny County Health Department will offer H1N1 vaccinations to those in the high-risk categories.

The clinics will be held from 10 a.m. to 4 p.m. at Chartiers Valley High School, Collier; McKeesport Area High School; North Allegheny High School, McCandless; and Pittsburgh Schenley High School, Shadyside.

Mr. Cole said about 3,500 doses will be available at each clinic, or 14,000 to 15,000 doses county-wide. Each clinic will have 45 to 50 people available to provide vaccines or assist in the process. Each patient must complete a vaccination consent form, which is available online at the www.achd.net.

To date, five people, all of whom had underlying medical problems, have died from H1N1 in Allegheny County, with a sixth case awaiting confirmation. They include three women and three men ranging in age from 26 to 57.

Locally, the H1N1 epidemic hit its peak in late October, with 18 percent of all emergency-room visits involving patients with flu-like symptoms, including coughing or respiratory problems and fever. By yesterday, that level had dropped to 4 percent of all emergency-room cases in the eight hospitals included in the health department's weekly survey.

But health officials said there still are many cases of H1N1 in the area and across the nation, and they said the unpredictable flu could return this winter in another wave. Forty-three states still are reporting H1N1 cases, down from 46 states last week.

"We can't predict exactly what's going to happen over the weeks or months ahead," Dr. Schuchat said. "Nothing is typical about this year's influenza. We may have weeks and months of a lot of disease ahead of us."

• New resistant strain of swine flu reported. Page A-2

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